Hydroprocessing reactor to lower pressure drop and extend catalyst life

ABSTRACT

A reactor for accommodating high contaminant feedstocks includes a reactor vessel having an inlet for introducing a feedstock containing contaminants into an interior of the reactor vessel. A basket is located within the reactor vessel interior and contains a particulate material for removing contaminants from the feedstock to form a purified feedstock that is discharged to a purified feedstock outlet. A catalyst is located within the reactor vessel and in fluid communication with the purified feedstock outlet of the basket for contacting the purified feedstock to form a desired product.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/900,043, filed Jun. 12, 2020, now U.S. Pat. No. 10,981,142, whichclaims the benefit of U.S. Provisional Patent Application No.62/861,038, filed Jun. 13, 2019, each of which is hereby incorporated byreference in its entirety for all purposes.

BACKGROUND

In hydroprocessing, refiners encounter many feedstocks that contain highlevels of a variety of impurities or contaminants. These contaminantsmay include gums, resins, metals, etc., commonly found in feedstockssuch as petroleum resids, heavy vacuum gas oil (VGO), bunker fuel,distillers corn oil (DCO), tallow, vegetable oils, including usedcooking oils, etc. These contaminants pose a problem for refinersbecause in high concentrations these contaminants are extremelydetrimental to catalysts. Catalyst deactivation, poisoning, plugging,coking, and sintering are chief concerns for refiners because of thegreat cost involved and the enormous impact of catalyst activity onproduct outcomes.

In conventional hydroprocessing, trickle-bed reactors distribute aliquid reactant evenly over the surface of a catalyst bed, or through alayer of trap, support material, or grading placed over a catalyst bedfor the purpose of removing contaminants. The cross-sectional area ofcatalyst bed, layer of trap, support material, or grading available tocontact the reactants is equal to the cross-sectional area of thereaction vessel, generally a circle, such that the effective contactarea, A_(c), is represented by Equation (1) below:A _(c) =πr ²  (1)where r is the radius of the reaction vessel, equal to D_(r)/2, whereD_(r) is the interior diameter of the reaction vessel.

Because the reactant must flow from the top down through the catalystbed, the removed contaminants are concentrated at the top region of thecatalyst bed or layer of trap, support material, or grading. This causesplugging to occur because the level of contaminants in the top region ofthe catalyst bed or layer of trap, support material, or grading becomesso high that the entire process is compromised, even though thecatalyst, trap, support material, or grading in the middle or lowerregions of the reactor have full functionality. Plugging, at anylocation in the reactor, causes pressure drop inside the reactor, makingit difficult to control the reaction and greatly affecting productoutcomes. The process must be halted, and fresh catalyst or supportmaterial must be added. With high contaminant feedstocks, catalystplugging can occur in a matter of days or weeks, rather than months oryears. Replacing catalyst this frequently is not economically feasible.As a result, there is a great need for a reactor design that will morefully utilize the entire volume of catalyst, and any optional layers ofsupport material, to extend the usable life of the catalyst and increaseprocess run times, especially for high contaminant feedstocks. There isalso a need for a reactor design that will minimize pressure drop withinthe reactor, whether due to normal operating conditions or as a resultof plugging in the reactor.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of particular embodiments of theinvention, and the advantages thereof, reference is now made to thefollowing descriptions taken in conjunction with the accompanyingfigure, in which:

FIG. 1 is a longitudinal cross-sectional schematic of a reactor foraccommodating high contaminant feedstocks configured in accordance withparticular embodiments of the invention;

FIG. 2 is a longitudinal cross-sectional schematic of another embodimentof a reactor for accommodating high contaminant feedstocks configured inaccordance with particular embodiments of the invention;

FIG. 3 is a longitudinal cross-sectional schematic of alternateembodiment of reactor for accommodating high contaminant feedstocksemploying a single reaction zone and a segregated basket configured inaccordance with particular embodiments of the invention;

FIG. 4 is a transverse cross-section schematic of the reactor of FIG. 3; and

FIG. 5 is a schematic representation of a system utilizing ametal-removal pretreatment reactor in combination with a reactor foraccommodating high contaminant feedstocks configured in accordance withparticular embodiments of the invention.

DETAILED DESCRIPTION

Disclosed herein are improved reactors that distribute liquid reactantsover the entire circumferential surface and length of the catalyst bedor layer of support material, thus extending process run times andcatalyst life, minimizing/delaying plugging, and minimizing pressuredrop throughout the reactor. The reactors are suitable for any number ofpetroleum or non-petroleum feedstocks, but especially suited for usewith feedstocks wherein impurities or contaminants are of significantconcern. These may include, but are not limited to, tallow, beef tallow,distillers corn oil, used cooking oil, pyrolysis oils, heavy VGO's,vacuum resids from petroleum processing, bunker fuel,triglyceride-containing feedstocks, etc. The contaminants may be gums,resins, and/or metal contaminants that are present in the feed.

The improved reactors are for use in hydroprocessing or similarprocesses. The feedstock, or liquid reactant, is combined with hydrogengas, and, optionally, a solvent or diluent such as heavy naphtha,propane, butane, pentane, light hydrocarbons, light distillates,naphtha, diesel, VGO, previously hydroprocessed stocks, or combinationsthereof, inside a reaction vessel containing at least one of a catalyst,system of catalysts, trap, support material, or grading, or acombination of these materials. The feedstock, hydrogen gas, and anydiluent may be combined inside the reaction vessel or combined beforeentering the vessel. The temperature and pressure inside the vesselshould be maintained at typical operating conditions forhydroprocessing, e.g., 250° F. to 850° F. and 0 psig to 3000 psig.

In certain instances the temperature inside the reaction vessel may befrom at least, equal to, and/or between any two of 250° F., 260° F.,270° F., 280° F., 290° F., 300° F., 310° F., 320° F., 330° F., 340° F.,350° F., 360° F., 370° F., 380° F., 390° F., 400° F., 410° F., 420° F.,430° F., 440° F., 450° F., 460° F., 470° F., 480° F., 490° F., 500° F.,510° F., 520° F., 530° F., 540° F., 550° F., 560° F., 570° F., 580° F.,590° F., 600° F., 610° F., 620° F., 630° F., 640° F., 650° F., 660° F.,670° F., 680° F., 690° F., 700° F., 710° F., 720° F., 730° F., 740° F.,750° F., 760° F., 770° F., 780° F., 790° F., 800° F., 810° F., 820° F.,830° F., 840° F., and 850° F.

In some applications, the operating pressure of the reactor may be fromat least, equal to, and/or between any two of 0 psig, 10 psig, 20 psig,30 psig, 40 psig, 50 psig, 60 psig, 80 psig, 90 psig, 100 psig, 110psig, 120 psig, 130 psig, 140 psig, 150 psig, 160 psig, 170 psig, 180psig, 190 psig, 200 psig, 250 psig, 300 psig, 350 psig, 400 psig, 450psig, 500 psig, 550 psig, 600 psig, 650 psig, 700 psig, 750 psig, 800psig, 850 psig, 900 psig, 950 psig, 1000 psig, 1050 psig, 1100 psig,1150 psig, 1200 psig, 1200 psig, 1250 psig, 1300 psig, 1350 psig, 1400psig, 1450 psig, 1500 psig, 1550 psig, 1600 psig, 1650 psig, 1700 psig,1750 psig, 1800 psig, 1850 psig, 1900 psig, 1950 psig, 2000 psig, 2050psig, 2100 psig, 2150 psig, 2200 psig, 2200 psig, 2250 psig, 2300 psig,2350 psig, 2400 psig, 2450 psig, 2500 psig, 2550 psig, 2600 psig, 2650psig, 2700 psig, 2750 psig, 2800 psig, 2850 psig, 2900 psig, 2950 psig,and 3000 psig.

It should be noted in the description, if a numerical value,concentration or range is presented, each numerical value should be readonce as modified by the term “about” (unless already expressly somodified), and then read again as not so modified unless otherwiseindicated in context. Also, in the description, it should be understoodthat an amount range listed or described as being useful, suitable, orthe like, is intended that any and every value within the range,including the end points, is to be considered as having been stated. Forexample, “a range of from 1 to 10” is to be read as indicating each andevery possible number along the continuum between about 1 and about 10.Thus, even if specific points within the range, or even no point withinthe range, are explicitly identified or referred to, it is to beunderstood that the inventor appreciates and understands that any andall points within the range are to be considered to have been specified,and that inventor possesses the entire range and all points within therange.

Optionally, an additive may be combined with the feedstock and hydrogengas to enhance removal of the impurities or contaminants. Non-limitingexamples of the additive may include hydrogen sulfide (H₂S), bisulfide,thiols, dodecanethiol, sulfur-containing vent gases (e.g., H₂S, etc.),etc. These are discussed more fully later on.

The reactor comprises a basket within a reaction vessel. The basket maybe cylindrical in shape and may have a diameter that is less than thatof the reaction vessel, and may be formed from a material that willconstrain solid matter but allow gases and liquids to flow freelythrough it. This may include a metal mesh or screen material. The basketmaterial can be selected such that the percentage of open area in thematerial yields an optimal pressure drop across the basket material toensure proper distribution of gases and liquids over the entire lengthof the basket. The basket is filled with particulate matter that servesto remove contaminants from the liquid reactant. This particulate mattermay include trap, support material, or grading, catalyst, or acombination of these materials. Such materials may include such thingsas sand, gravel, catalyst, spent catalyst, off-spec catalyst,regenerated catalyst, catalyst carriers, ceramic rings, etc., andcombinations of these.

The basket may be filled completely with particulate matter, or thebasket may be structured to form a cylindrical annulus or ring ofmaterial, with a cylindrical void or column of space running verticallythrough the center of the basket. Furthermore, the basket mayincorporate annular walls to segregate multiple types of differentparticulate matter within the basket. The basket may extend alongsubstantially the entire length of the reaction vessel, or it may beplaced in a compartment above a catalyst bed inside a segregatedreaction vessel. The basket may be covered with a lid or cover thatcovers the entire diameter of the basket so that the upper end of thebasket is closed to prevent passage of fluids through the upper end ofthe basket. In other embodiments, the upper end of the basket may have acover or lid having apertures or openings that allows some amount offluids to pass downward through the upper end of the basket.

In certain embodiments, where the basket has a cylindricalconfiguration, the outer surface area of catalyst bed, layer of trap,support material, or grading available to contact the reactants is equalto the surface area of the outer walls of the basket, such that theeffective contact area, A_(c), is equal to Equation (2) below:A _(c) =πD _(b) L  (2)where D_(b) is the outer diameter of the basket and L is the length ofthe basket. It should be noted, that where the basket has anon-cylindrical configuration, the contact area may be differentlycalculated. As can be appreciated, the area Ac according to Equation (2)can be configured so that it has a much larger contact area than thatprovided by the contact area A_(c) of Equation (1) as provided in theprior art reactors.

The feedstock to be treated and hydrogen, along with any desireddiluents or additives, are introduced into the reactor inlet. A liquiddistributor is used to disperse liquid outward, toward the walls of thereaction vessel. The liquid flows outward toward the walls of thereaction vessel and down into the circumferential gap between the wallsof the reaction vessel and the outer walls of the basket. From thecircumferential gap, liquid is then drawn through the basket to theoutlet near the base of the basket. The outlet may be in fluidcommunication with the cylindrical void or column of space runningvertically through the center of the basket, if one is provided.Optionally, the liquid may then be distributed over a catalyst bed in alower compartment of the reaction vessel. The product exits the reactorthrough an outlet near the bottom of the reaction vessel.

Where the reactor vessel and basket are cylindrical, the circumferentialgap or annular space ε₀ between the reaction vessel and the exterior ofthe basket can be characterized by Equation (3) below:ε₀=(D _(r) −D _(b))/2  (3)where D_(r) is the interior diameter of the reactor vessel and D_(b) isthe diameter of the outer wall of the basket.

The circumferential gap may be calculated differently fornon-cylindrical reactor vessels and baskets. The circumferential gap ε₀impacts the velocity at which the reactants move through the reactor.The basket should be sized to provide a circumferential gap ε₀ that willfacilitate operation within the range of desired flow rates.

In one embodiment, the reactor comprises a segregated reaction vessel.The basket may be a cylindrical shell or cylindrical annulus thatextends along the length of an upper compartment of the reaction vessel.The basket walls are fluid permeable or formed from a material that willconstrain solid matter but allows gases and liquids to flow freelythrough them. The basket may have a fluid-impenetrable top and bottom,only permitting liquids or gasses to pass through the bottom of thebasket at or through a basket outlet. The basket contains trap, supportmaterial, or grading, or optionally, a combination of trap, supportmaterial, or grading, and catalyst with the trap, support material, orgrading forming the outer circumferential layer of particulate matterwithin the basket and the catalyst forming an inner circumferentiallayer of the particulate matter of the basket, with the layers separatedby a fluid-penetrable or permeable barrier or layer of material orstructure that constrains the different solid materials but allows gasesand liquids to flow freely through it. The basket may incorporate aplurality of different radially spaced annular or circumferential layersor beds of particulate matter.

The reactants, comprised of a feedstock and hydrogen, along with anydesired diluents or additives, is introduced into the upper compartmentof the reaction vessel through the reactor inlet. This may beaccomplished with or without the use of a liquid distributor. Withrespect to the liquid distributor, this may be located below and influid communication with the reactor inlet for discharging the feedstockradially outward towards the interior walls of the reactor vessel. Inmost instances the reactors are oriented so that overall liquid flow isgenerally directed downward from top to bottom through the reactor. Thereactants may flow out, over the impenetrable top covering of the basketor through a distributor assembly where they are directed radiallyoutward toward the walls of the reaction vessel, and down into thecircumferential gap or annular flow space formed between the walls ofthe reaction vessel and the outer walls of the basket. The reactants arethen drawn or flow radially inward through the basket, reacting with theparticulate matter inside the basket to form a partially reacted orpurified liquid having a reduced quantity of contaminants prior topassing to the catalyst bed.

After passing through the basket, the partially reacted liquid havingreduced contaminant content then passes through an outlet at the base ofthe upper compartment of the reaction vessel to a lower compartment ofthe reactor containing a catalyst bed. The partially reacted liquid maybe distributed evenly over the surface of the catalyst bed by adistributor and reacts with the catalyst to form the desired product.Optionally, the reaction vessel may contain multiple lower compartmentscontaining catalyst beds in order to form the desired product. Theproduct is removed from the reactor near the base of the reaction vesselthrough a reactor outlet.

In another embodiment, the basket may be a cylindrical shell orcylindrical annulus that extends along all or a portion of the length ofthe reaction vessel. The basket may be a segregated basket that containstrap, support material, or grading, catalyst, or a combination of trap,support material, or grading and catalyst with the support materialforming an outer annular or circumferential layer of particulate matterwithin the basket and the catalyst forming an inner annular orcircumferential layer of the particulate matter of the basket. Thelayers are separated by a fluid penetrable or permeable barrier or layerof material or structure that constrains solid matter but readily allowsgases and liquids to flow freely through it.

In certain instances, the basket may incorporate a plurality ofdifferent radially spaced annular or circumferential layers of differentparticulate matter. The reactants, comprised of a feedstock andhydrogen, along with any desired diluents or additives, is introducedinto the reaction vessel through the reactor inlet. This may beaccomplished with or without the use of a liquid distributor. Thereactants may flow over the impenetrable top covering the basket or outfrom the distributor radially outward toward the interior walls of thereaction vessel, and down into the annular space or circumferential gapformed between the walls of the reaction vessel and the basket. Thereactants are then drawn or flow radially inward through the basket,reacting with the different particulate matter inside the basket to formthe desired product. After passing through the basket, the product thenpasses through an outlet at the base of the reactor.

Referring to FIG. 1 a cross-sectional schematic of a reactor 10configured as a segregated reaction vessel is shown. The reactor 10 iscomprised of a reaction vessel 12 having an upper compartment 14containing a basket 16 and a lower compartment 18 containing a catalystbed. The basket 16 in the upper compartment 14 forms a fluid penetrableor fluid permeable barrier and is formed from a material or structurethat will constrain solid particulate matter but allows gases andliquids to flow freely through it, while containing a solid particulatematter, such as those described previously, that serves to removecontaminants such as gums, metals, resins, etc. The area within thebasket 16 containing the particulate matter constitutes a contaminantremoval zone or pretreatment bed 20 of the reactor 10. The basket 16 isshown covered by a fluid impermeable solid top or cover 22.

A feedstock 24 containing contaminants, hydrogen gas 26, and a diluent28 are each introduced into an inlet 30 of the reactor 10 by adistributor assembly 32 in the upper compartment 14 of the reactionvessel 12. The combined feeds 34 are dispersed radially outward towardthe walls of the reaction vessel 12 and flow over the fluid impenetrablesolid top 22 that covers the basket 16. The combined feeds 34 may flowdown and over the cover 16 into the circumferential gap 60 between thewalls of the reaction vessel 12 and the walls of the basket 16.Alternatively, the feeds 34 may be discharged from the distributorassembly 32 radially outward towards the interior walls of the reactorvessel 12. The combined feeds 34 then flow through the walls of thebasket 16 and through the solid particulate matter forming thepretreatment bed 20 contained within the basket 16 wherein contaminantsare removed in a contaminant-removal pretreatment.

The purified or pretreated feeds or reactants then flow out of an outlet36 of the basket 16 of the upper compartment 14 of the reaction vessel12 and through a conduit outlet 38 at the base of the upper compartment14. The purified feed then flows into the lower compartment 18 of thereaction vessel 12 through a second distributor assembly 40. Thepurified feed is dispersed evenly over the surface of the catalyst bed42 (e.g., a hydroprocessing catalyst) where the reactants react to forma product that flows out of an outlet 44 of the reactor 10 at the baseof the reactor 10.

FIG. 2 shows a longitudinal cross-sectional schematic of anotherembodiment of a reactor 50. The reactor 50 includes a reactor vessel 52having an inlet 54 for introducing a contaminant-containing feedstock 56to be processed, along with hydrogen gas 58, and any optional diluent 60or other additives. The interior of the reactor vessel is defined by aninterior wall 62 of the reactor vessel 52. A distributor assembly 64 ofthe reactor 50 is located below and in fluid communication with theinlet 54 for discharging the combined feeds 66 radially outward towardsthe interior walls 62 of the reactor vessel 52.

A basket 68 is located within an upper compartment 70 of the reactorvessel 52 interior and below the distributor assembly 64. The basket 68has a fluid permeable outer wall 72 and a fluid permeable inner wall 74that is spaced radially inward from the outer wall 72 to define anannular interior space 76 of the basket 68. The annular interior space76 of the basket 68 contains a particulate material, such as thosedescribed previously, suitable for removing contaminants from thefeedstock to form a contaminant removal zone or pretreatment bed 78. Theouter wall 72 of the basket 68 is spaced radially inward from theinterior wall 62 of the reactor vessel to define an annular flow space80 between the outer wall 72 of the basket 68 and the interior wall 62of the reactor vessel 52.

The distributor assembly 64 may be configured with two spaced apartupper and lower plates or disks 82, 84, which may be circular in shapeand parallel or substantially parallel to one another. The plates 82, 84are joined together along their outer perimeters by a circumferentialwall 86. Radially spaced apart apertures, slots or openings 88 areprovided around all or a portion of the circumferential wall 86 to allowthe combined feed 66 to be discharged from the distributor assembly 64radially outward in all directions (i.e., 360°) towards the interiorwalls 62 of the reactor vessel 52. This discharge of the feed from thedistributor assembly 64 is oriented generally perpendicular to a centrallongitudinal axis 90 of the reactor vessel 52 that extends along itslength. In other embodiments, the feed discharged from the distributorassembly 64 may be oriented at a non-parallel angle to the axis 90, suchas from 30° to 90° relative to the axis 90.

The combined feeds 66 introduced into the reactor vessel 52 from thedistributor assembly 64 flow through the annular flow space 80 andradially inward through the annular interior space 74 of the basket 68and through the pretreatment bed 78 to facilitate removal ofcontaminants from the feedstock to form a pretreated or purifiedfeedstock 92. The fluid permeable inner wall 74 forms a pretreated orpurified feedstock outlet of the basket 68 and defines a central conduit94 that extends along the length of the basket 64. The central conduit94 may be concentric or non-concentric with the longitudinal axis 90.The central conduit 94 has a conduit outlet 96 for discharging thepurified feedstock 92 through a fluid impermeable floor or partition 98of the upper compartment 70 that prevents axial fluid flow through thebasket 68 and annular space 80.

The pretreated or purified feed 92 then flows into a lower compartment100 of the reaction vessel 52 through a second distributor assembly 102.The purified feed 92 is dispersed evenly over a catalyst bed 104containing a selected catalyst (e.g., a hydroprocessing catalyst)located within the lower compartment 100 where the reactants react toform a desired product 106 that flows out of an outlet 108 of thereactor 50 at the base of the reactor 50.

In the design and configuration of the reactor 50 and basket 68 certaincriteria should be met. If the liquid flow velocity at or near the topof the annular flow space 80 of the upper compartment 70 is zero due tothere being no liquid present, a maldistribution is created through thepretreatment bed 78 within the interior space 76 of the basket 68.Instead, the liquid feed will tend to accumulate in the lower portion ofthe annular flow space 80 so that it only passes through lower portionof the basket 68 pretreatment bed 78. This essentially reduces theeffective contact area of the basket. Without proper configuration, asmuch as 80% of the liquid feed, as an example, may pass through thelower one-third of the basket 68, while the remaining 20% of the liquidfeed passes through the upper two-thirds of the basket 68. This canresult in premature plugging of the pretreatment bed 78 in the lowerone-third of the basket.

To ensure that this does not happen, certain design parameters must bemet. This includes ensuring that all liquid flow velocity changes arethe same throughout the pretreatment operation. Such liquid flowvelocities include the velocity at the reactor inlet 54, the radialvelocity at the distributor assembly 64, the velocity down the annularflow space 80, the radial velocity through the pretreatment bed 78, andthe velocity through the central conduit 94. By way of example, if thevelocity of fluid flowing through the reactor inlet 54 is 20 ft/s, thenthe fluid velocity through the distributor assembly 64, the velocitydown the annular flow space 80, the radial velocity through thepretreatment bed 78, and the velocity through the central conduit 94should also be 20 ft/s or approximately so.

To achieve this, it is important that the reactor vessel and distributorassembly are configured so that liquid fluid flow of the combined feedsfrom the distributor assembly provides a stagnation head h_(s) thatmeets the criteria represented by Equation (4) below:h _(s) ≤D _(r)/2  (4)

The circumferential gap ε₀ also comes into play and should meet therelationship with respect to D_(r) and D_(b) represented in Equation(3), described previously. This gives the liquid velocity in the annularflow space 80 the same velocity of the radially discharged liquidsdischarged from the distributor assembly 64.

The fluid permeable inner wall 74, which forms an outlet of the basket68, should also have a sufficient open area to allow the passage offluids therethrough to avoid a significant maldistribution of liquidthrough the particulate matter of the pretreatment bed 78. The innerwall 74 is therefore configured with a sufficient open area to provide aselected pressure drop ΔP across the inner wall 74. This pressure dropΔP should range from 2 to 10 times the velocity head h_(v) at theconduit outlet 96. This may be represented by the following Equation (5)below:ΔP=C·h _(v)  (5)where C ranges from 2 to 10. In certain embodiments, C may be at least,equal to, and/or between any two of 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6,2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0,4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4,5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8,6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2,8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6,9.7, 9.8, 9.9, and 10.0.

The velocity head h_(v) may be determined according to Equation (6)below:h _(v) =V _(o) ²/2G _(c)  (6)where V_(o) is the velocity of liquid flow at the conduit outlet 96 andG_(c) is the gravitational acceleration constant (i.e., G_(c)=32.17ft/s²).

Another relationship that does not necessarily relate to the overallfunctionality of the reactor but relates to the life of the pretreatmentbed 78 is the length L_(b) of the basket. Assuming that plugging of thepretreatment bed is directly proportional to the area of flow throughthe pretreatment bed or basket, the higher the area of flow the longerthe pretreatment bed should last. A selected or optimal length L_(b) forthe basket may be determined from the following Equation (7) below:L _(b)=(D _(r) ²/4D _(b))(ψ)  (7)where D_(r) is the interior diameter of the reactor vessel, D_(b) is thediameter of the fluid permeable outer wall of the basket, and ψ is acoefficient corresponding to the cycle life of the pretreatment bed,which may range from 1 to 20, with L_(b)≤L_(r), where L_(r) is thelength of the reactor vessel. In certain embodiments, w may be at least,equal to, and/or between any two of 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6,1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0,3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4,4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8,5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2,7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6,8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0,10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11.0, 11.1,11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 12.0, 12.1, 12.2, 12.3,12.4, 12.5, 12.6, 12.7, 12.8, 12.9, 13.0, 13.1, 13.2, 13.3, 13.4, 13.5,13.6, 13.7, 13.8, 13.9, 14.0, 14.1, 14.2, 14.3, 14.4, 14.5, 14.6, 14.7,14.8, 14.9, 15.0, 15.1, 15.2, 15.3, 15.4, 15.5, 15.6, 15.7, 15.8, 15.9,16.0, 16.1, 16.2, 16.3, 16.4, 16.5, 16.6, 16.7, 16.8, 16.9, 17.0, 17.1,17.2, 17.3, 17.4, 17.5, 17.6, 17.7, 17.8, 17.9, 18.0, 18.1, 18.2, 18.3,18.4, 18.5, 18.6, 18.7, 18.8, 18.9, 19.0, 19.1, 19.2, 19.3, 19.4, 19.5,19.6, 19.7, 19.8, 19.9, and 20.0.

Referring to FIG. 3 , another embodiment of a reactor for accommodatinghigh contaminant feedstocks is shown. This shows a longitudinalcross-sectional schematic of a reactor 110. The reactor 110 isconfigured similarly to the reactor 50 of FIG. 1 but employs a singlereaction zone and a segregated basket to carry out both contaminantremoval and processing of the feedstock to form the desired finalproduct. The design criteria and relationships described above alsoapply to this configuration, as well.

The reactor 110 comprises a reaction vessel 112 containing a segregatedbasket 114 in the shape of a cylindrical annulus. The basket 114 isdefined by an circumferential outer wall 116 formed as afluid-penetrable or permeable barrier formed from a material orstructure that will constrain solid particulate matter but allows gasesand liquids to flow freely through the outer wall 116. The outer wall116 forms a fluid inlet of the basket 114. The basket 114 furtherincludes and contains an inner intermediate circumferential segregatingwall or structure 118 spaced radially inward from the outer wall 116 ofthe basket 114. The wall 118 may be configured similarly or differentlyand from the same or different materials as the outer wall 116 of thebasket 114. The outer wall 116 of the basket 114 and the inner wall 118defines an outer circumferential annular space 120 of the basket 114.

A further fluid permeable circumferential innermost wall 122 of thesegregated basket 114 is spaced radially inward from the intermediatewall 118. The circumferential area located radially inward from theinner intermediate wall 118 and the innermost wall 122 forms an innercircumferential annular space 124 of the basket 114. The outer annularspace 120 of the basket 114 is filled with a solid particulate material,such as those described previously for contaminant removal, which formsa contaminant removal zone or pretreatment bed or layer 126. Thepretreatment bed or layer 126 serves to remove contaminants such asgums, metals, resins, etc.

The innermost annular space 124 of the basket 114 is filled with aprocessing catalyst to form a catalyst bed or layer 128 (e.g., ahydroprocessing catalyst) that forms a reaction zone. The fluidpermeable intermediate wall 118 thus forms an outlet of the contaminantremoval zone 124 of the basket 114. The basket 114 may be covered by animpermeable lid or cover 130. In other embodiments, the cover 130 may bepermeable to allow some amount of feedstock downflow.

The innermost wall or structure 122 may be configured similarly ordifferently and from the same or different materials as the outer wall116 and/or intermediate wall 118 of the basket 114 for constrainingsolid matter 124 but allowing gases and liquids to flow freely throughthe innermost wall 122. The innermost wall 122 retains the particulatecatalyst material of the catalyst bed 128 in the annular space 124 andfurther defines a central conduit 132 that is free from any particulatesolid material. The innermost wall 122 thus forms an outlet of thecatalyst bed 128. The central conduit 132 may be concentric ornon-concentric with a longitudinal axis 134 of the reactor vessel 112.The conduit 132 is in fluid communication with an outlet 136 located atthe base of the reactor vessel 112.

A contaminated feedstock 138 to be processed, hydrogen gas 140, anoptional additive 142, and an optional diluent 144 are introduced intoan inlet 146 of the reactor 110 into the interior of the reactor vessel112, which is defined by an interior wall 148, as combined feeds 150. Adistributor assembly 152 of the reactor 110 is located below and influid communication with the inlet 146 for discharging the combinedfeeds 150 radially outward towards the interior walls 148 of the reactorvessel 52.

The reactants or combined feed 150 is dispersed radially outward fromthe distributor assembly 152 toward the walls of the reaction vessel112. The distributor assembly 152 may be configured similarly to thedistributor assembly 64 of the reactor 50 of FIG. 2 . The combined feedsflow down through an annular flow space 156, which is defined by theinterior walls 148 of the reactor vessel and the outer wall 116 of thebasket 114.

The feed flows from the annular flow space 156 and radially inwardthrough the outer annular space 120 of the basket 114 and through thepretreatment bed 126 to facilitate removal of contaminants from thefeedstock to form a purified feedstock. The fluid permeable intermediatewall 118 thus forms a purified feedstock outlet of the basket 114. Afluid impermeable floor or barrier at the bottom or base of the reactorvessel 112 may be provided to prevent axial fluid flow through thebasket 114 and annular space 156.

The purified feedstock continues to flow through the innermost annularspace 124 and through the catalyst bed 128 of the basket 124 to form aproduct 158 that flows into the central conduit 132 that forms an outletof the basket 114. The central conduit 132 extends vertically throughthe center of the basket 114. The product 90 then flows from the centralconduit 132 of the basket 114 to reactor outlet 134 at the base of thereactor 110.

Referring to FIG. 4 a transverse cross-sectional schematic of thereactor 110 containing the single reaction zone and the segregatedbasket 114 in the shape of a cylindrical annulus is shown. The reactor110 is comprised of the reaction vessel 112 having a diameter D_(r).Within the reaction vessel 112 is the basket 114 having a diameter D_(b)and containing an intermediate circumferential segregating wall 118. Thecircumferential gap or annular space 156 (Eo) is formed between theinterior walls 148 of the reaction vessel 112 and the outer permeablewall 116 of the basket 114. At the center of the reaction vessel 112 isthe central conduit 132.

In certain applications, the reactors for accommodating high contaminantfeedstocks, such as the reactors 10, 50, and 110, may be used incombination with a further metal-removal treatment process. Themetal-removal treatment process can be used to treat the contaminatedfeedstock prior to its being introduced into the reactors employing thecontaminant removal baskets, as have been described. Alternatively, themetal-removal treatment process can be used to treat a pretreated orpurified feedstock after it has been discharged from the outlet of thecontaminant removal basket and prior to its introduction into thereaction zone for producing the desired product.

The metal-removal treatment process provides a simple and inexpensivemethod for removing impurities from lower quality refinable feedstockscontaining a large number of impurities or contaminants. Thecontaminants may be metal contaminants that are present in the feed.These metals may include, but are not limited to, nickel (Ni), vanadium(V), phosphorus (P), iron (Fe), etc. The metal contaminants may bepresent in the feedstock in an amount from at least, equal to, and/orbetween any two of 1 ppm, 2 ppm, 3 ppm, 4 ppm, 5 ppm, 6 ppm, 7 ppm, 8ppm, 9 ppm, 10 ppm, 15 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70ppm, 80 ppm, 90 ppm, 100 ppm, 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350ppm, 400 ppm, 450 ppm, 500 ppm, 550 ppm, 600 ppm, 650 ppm, 700 ppm, 750ppm, 800 ppm, 850 ppm, 900 ppm, 950 ppm, and 1000 ppm or more by weightof the feedstock.

In the metal-removal pretreatment process, the feedstock is combinedwith a selected amount of an additive. The additive is that which iscapable of reacting or complexing with the metal contaminants containedin the feedstock to form a precipitate. This can include sulfur, orsulfur-containing compounds that generate sulfur for reacting with themetal contaminants, although non-sulfur additives that provide similarreactions with metal contaminants may also be used. Non-limitingexamples of the additive may include hydrogen sulfide (H₂S), bisulfide,thiols, dodecanethiol, sulfur-containing vent gases (e.g., H₂S, etc.),etc. The quantity of additive required for the pretreatment process maybe proportional to the amount of metal and quantity of contaminantsdesired to be removed from the feedstock.

In certain embodiments, the additive may be used in an amount of fromgreater than 0 to 10 times or more than that necessary to react with allthe metal contaminants to be removed from the feedstock. Thus, theadditive may be added in an amount that is in stoichiometric excess ofthe amount needed to complex with the metal contaminants of the feed. Incertain embodiments, the amount of additive used may be an amount fromat least, equal to, and/or between any two of greater than 0.1, 0.2,0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 thanthat necessary to react with the metal contaminants to be removed fromthe feedstock.

With respect to the additive of sulfur, the sulfur will react with themetal contaminants to form metal sulfides. As an example, if nickel (Ni)is one of the contaminants to be removed, a sulfur additive may be addedthat is in stoichiometric excess of the amount needed to complex withall the nickel contained in the feed to form nickel sulfide (NiS). Thus,if the sulfur additive is used in an amount of two times that necessaryto react with nickel contaminants, then an additive containing 2 molesof sulfur for every one mole of nickel in the feedstock would be used.In another example, a feedstock containing 100 ppm metal contaminantsmay be used in an amount of 1000 ppm sulfur or other additive.

Hydrogen gas may also be used in the pretreatment. The hydrogen gas maybe used in quantities of 0 scf/bbl to 1000 scf/bbl of feedstock. Inparticular embodiments, the amount of hydrogen gas used may be an amountfrom at least, equal to, and/or between any two of 0 scf/bbl, 10scf/bbl, 20 scf/bbl, 30 scf/bbl, 40 scf/bbl, 50 scf/bbl, 60 scf/bbl, 70scf/bbl, 80 scf/bbl, 90 scf/bbl, 100 scf/bbl, 150 scf/bbl, 200 scf/bbl,250 scf/bbl, 300 scf/bbl, 350 scf/bbl, 400 scf/bbl, 450 scf/bbl, 500scf/bbl, 550 scf/bbl, 600 scf/bbl, 650 scf/bbl, 700 scf/bbl, 750scf/bbl, 800 scf/bbl, 850 scf/bbl, 900 scf/bbl, 950 scf/bbl, and 1000scf/bbl. The added hydrogen is used to react with sulfur-containingcompounds in the feed or reaction mixture so that it forms hydrogensulfide or other reactive sulfur-containing compounds capable ofreacting with metals in the feedstock. The amount of hydrogen added maytherefore depend upon the sulfur content of the feed or reactionmixture.

The feedstock, additive, and optional hydrogen can be combined insidethe metal-removal reaction vessel or combined before entering thevessel. The vessel may be heated to or operated at a temperature in therange of 250° F. to 850° F. In certain embodiments, the vessel may beheated to or operated at temperatures of from at least, equal to, and/orbetween any two of 250° F., 260° F., 270° F., 280° F., 290° F., 300° F.,310° F., 320° F., 330° F., 340° F., 350° F., 360° F., 370° F., 380° F.,390° F., 400° F., 410° F., 420° F., 430° F., 440° F., 450° F., 460° F.,470° F., 480° F., 490° F., 500° F., 510° F., 520° F., 530° F., 540° F.,550° F., 560° F., 570° F., 580° F., 590° F., 600° F., 610° F., 620° F.,630° F., 640° F., 650° F., 660° F., 670° F., 680° F., 690° F., 700° F.,710° F., 720° F., 730° F., 740° F., 750° F., 760° F., 770° F., 780° F.,790° F., 800° F., 810° F., 820° F., 830° F., 840° F., and 850° F.

The metal-removal reaction vessel may be operated at pressure of from 0psig to 3000 psig. In certain instances, the metal removal reactionvessel may be operated at fairly low pressures of from 0 psig to 150psig. This reduced pressure may facilitate minimizing the amount ofdowntime of the reactor when it must be shut down for maintenance, etc.In particular embodiments, the vessel may be operated at pressures offrom at least, equal to, and/or between any two of 0 psig, 10 psig, 20psig, 30 psig, 40 psig, 50 psig, 60 psig, 80 psig, 90 psig, 100 psig,110 psig, 120 psig, 130 psig, 140 psig, 150 psig, 160 psig, 170 psig,180 psig, 190 psig, 200 psig, 250 psig, 300 psig, 350 psig, 400 psig,450 psig, 500 psig, 550 psig, 600 psig, 650 psig, 700 psig, 750 psig,800 psig, 850 psig, 900 psig, 950 psig, 1000 psig, 1050 psig, 1100 psig,1150 psig, 1200 psig, 1200 psig, 1250 psig, 1300 psig, 1350 psig, 1400psig, 1450 psig, 1500 psig, 1550 psig, 1600 psig, 1650 psig, 1700 psig,1750 psig, 1800 psig, 1850 psig, 1900 psig, 1950 psig, 2000 psig, 2050psig, 2100 psig, 2150 psig, 2200 psig, 2200 psig, 2250 psig, 2300 psig,2350 psig, 2400 psig, 2450 psig, 2500 psig, 2550 psig, 2600 psig, 2650psig, 2700 psig, 2750 psig, 2800 psig, 2850 psig, 2900 psig, 2950 psig,and 3000 psig.

Optionally, a catalyst or inert solid contained within the metal-removalreaction vessel may be used in the pretreatment. The catalyst may be anon-demetallization catalyst, such as a hydrotreating catalyst orsimilar catalyst. A low-activity demetallization catalyst can also beused in the pretreatment reactor in certain instances. Inert solids,which may be particulate solids, on which precipitated metals may bedeposited may also be used. In other applications, some low amount ofdemetallization catalyst may be used in the pretreatment method, buttypically no demetallization catalyst is used as may be used withconventional removal of metal contaminants. Such demetallizationcatalyst may also include those such as used in the contaminationremoval baskets, as have been described.

At the reaction conditions, the contaminant removal additive reacts withthe metal impurities. The reaction may be that which forms metalsulfides and reduced metals. The feedstock is altered in such a way thatthe pretreated feedstock becomes much more suitable for refining intothe desired product. Some additive/impurity reactions may result in theprecipitation of undesirable components, such as metal sulfides andreduced metals, from the liquid solution. Other additive/impurityreactions may result in the formation of desired compounds (i.e., usefulmetal-free organics), neutral compounds (i.e., non-useful metal-freeorganics, or other compounds (e.g., reduced-metal-content organics)that, while still undesirable, reduce the equipment and resources neededto produce the desired end-product from the refinable feedstock, whilealso lowering the risk of corrosion, catalyst deactivation, andequipment failure in the subsequent refining process to be utilized.This may also extend the life of the pretreatment beds used incontaminant removal reactors previously described, such as the reactors10, 50, and 110.

For reactions that result in the precipitation of metal andmetal-containing solids from the solution, a method of removing thesolids must be employed. A variety of methods can be employed eitherwithin the reaction vessel or after the reacted feedstock exits thereaction vessel. Some examples of methods for removing precipitatedsolids include, but are not limited to, saddles, ceramic saddles, guardcatalysts, filters, centrifuges, water wash, etc.

Desirable or undesirable gas phase products may be removed throughventing. After exiting the metal-removal reaction vessel, the treatedfeedstocks can then be processed to produce the desired fuels orspecialty chemical products using conventional refining processes withfewer, and ideally no, required equipment upgrades, additional refiningsteps, or significant resource requirements.

Referring to FIG. 5 a schematic flow diagram of an exemplarypretreatment system 160 employed with a reactor for accommodating highcontaminant feedstocks for removing contaminants is shown. The system160 includes a metal-removal reactor 162 formed by a reactor vessel 164having a reaction chamber 166 that defines a reaction zone. A refinablehydrocarbon feedstock 168 containing metal and other contaminants to betreated, metal-removal additive 170, and hydrogen gas 172 are introducedinto the reaction chamber 166 of the reactor 162. The different feeds168, 170, 172 may be added separately into the reactor 162 or may becombined upstream of the reactor 162 and introduced together into thereactor 162.

The feedstock 168 may be a petroleum and/or non-petroleum feedstockhaving high levels of metal and other contaminants. Petroleum feedstocksmay include petroleum resids, heavy vacuum gas oil (VGO), bunker fuel,etc. The non-petroleum feedstock may include materials derived from orbased on plant, vegetable, animal, and cellulosic materials, coal, andcombinations of such materials. These may include but are not limited totallow, beef tallow, bleachable fancy tallow, distillers corn oil, usedcooking oil, pyrolysis oil, triglyceride-containing feedstocks, etc.

The additive feed 170 is that which is capable of reacting or complexingwith metal contaminants contained in the feedstock to form a metalprecipitate. This may include sulfur or a sulfur generating compound(e.g., hydrogen sulfide, bisulfide, dodecanethiol, sulfur-containingvent gases (e.g., H₂S, etc.), etc.). The amount of additive used may bean amount from at least, equal to, and/or between any two of greaterthan 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 1, 2, 3, 4, 5, 6, 7, 8,9, and 10 than that necessary to react with the metal contaminants to beremoved from the feedstock.

A hydrogen feed 172 is hydrogen gas in quantities of 0 scf/bbl to 1000scf/bbl of feedstock may be fed to the reactor 162.

A catalyst bed 174 containing a non-demetallization catalyst, such as ahydrotreating catalyst or similar catalyst, a low-activitydemetallization catalyst, and/or inert solid material, for facilitatingthe pretreatment may be provided in the reaction chamber 166 of thevessel 164. In other embodiments, no catalyst is used in thepretreatment reactor 162.

The reactor 162 is operated at reaction conditions suitable for themetal-reducing pretreatment of the feedstock. This may include areaction temperature of from 250° F. to 850° F. and an operatingpressure of from 0 psig to 3000 psig, more particularly from 600 psig to1200 psig. In certain embodiments, low pressures of from 0 psig to 150psig may be used. At these conditions the metal-removal additive reactswith the metal impurities in the feedstock, which precipitate and arethen removed, so that the pretreated feedstock is more suitable forprocessing and refining downstream.

Pretreatment products include precipitated reaction products (e.g.,metal sulfides, reduced metals, etc.) resulting from the reaction ofcontaminants with the additive. These may be removed through thereaction vessel 162 through precipitated-solids stream 176. Theprecipitated solid stream 176 may be further processed to remove theprecipitated solids in solids separator unit 178, using those methodspreviously mentioned (e.g., saddles, ceramic saddles, guard catalysts,filters, centrifuges, water wash, etc.) where removed solids are removedfrom the pretreated feedstock as solids stream 180.

Gases, both desirable and undesirable, may be vented or removed from thereactor 162 through gas stream 182. Gases can include unreacted hydrogengas, hydrogen sulfide, gaseous light hydrocarbons, CO, CO₂, etc.

A pretreated product stream 184 having reduced contaminant content isremoved from the solids separator unit 178. The pretreated productstream 184 may have a reduced metal content that is reduced by an amountof from 1 wt. % to less than 100 wt. % of the contaminant content of thefeedstock prior to treatment. In certain embodiments, the pretreatedproduct stream 184 may have a reduced contaminant (or metal) content ofat least, equal to, and/or between any two of 1 wt. %, 2 wt. %, 3 wt. %,4 wt. %, 5 wt. %, 6 wt. %, 7 wt. %, 8 wt. %, 9 wt. %, 10 wt. %, 11 wt.%, 12 wt. %, 13 wt. %, 14 wt. %, 15 wt. %, 16 wt. %, 17 wt. %, 18 wt. %,19 wt. %, 20 wt. %, 21 wt. %, 22 wt. %, 23 wt. %, 24 wt. %, 25 wt. %, 26wt. %, 27 wt. %, 28 wt. %, 29 wt. %, 30 wt. %, 31 wt. %, 32 wt. %, 33wt. %, 34 wt. %, 35 wt. %, 36 wt. %, 37 wt. %, 38 wt. %, 39 wt. %, and40 wt. %, 41 wt. %, 42 wt. %, 43 wt. %, 44 wt. %, 45 wt. %, 46 wt. %, 47wt. %, 48 wt. %, 49 wt. %, 50 wt. %, 51 wt. %, 52 wt. %, 53 wt. %, 54wt. %, 55 wt. %, 56 wt. %, 57 wt. %, 58 wt. %, 59 wt. %, 60 wt. %, 61wt. %, 62 wt. %, 63 wt. %, 64 wt. %, 65 wt. %, 66 wt. %, 67 wt. %, 68wt. %, 69 wt. %, 70 wt. %, 71 wt. %, 72 wt. %, 73 wt. %, 74 wt. %, 75wt. %, 76 wt. %, 77 wt. %, 78 wt. %, 79 wt. %, 80 wt. %, 81 wt. %, 82wt. %, 83 wt. %, 84 wt. %, 85 wt. %, 86 wt. %, 87 wt. %, 88 wt. %, 89wt. %, 90 wt. %, 91 wt. %, 92 wt. %, 93 wt. %, 94 wt. %, 95 wt. %, 96wt. %, 97 wt. %, 98 wt. %, 99 wt. %, and less than 100 wt. % of thecontaminant content of the feedstock prior to treatment.

The pretreated product stream 184 is then delivered to a further reactoror system 186, such as those reactors 10, 50, 110, previously described,where it may be combined with hydrogen gas 188, and optionally a diluent190 for further contaminant removal and processing into fuels or otherspecialty chemicals or desired products. In the embodiment shown in FIG.5 , the reactor system 186 is that configured similarly to reactor 50,as has been disclosed.

While the invention has been shown in some of its forms, it should beapparent to those skilled in the art that it is not so limited, but issusceptible to various changes and modifications without departing fromthe scope of the invention based on experimental data or otheroptimizations considering the overall economics of the process.Accordingly, it is appropriate that the appended claims be construedbroadly and, in a manner, consistent with the scope of the invention.

We claim:
 1. A reactor for accommodating high contaminant liquidfeedstocks comprising: a reactor vessel having an inlet for introducinga liquid feedstock containing contaminants into an interior of thereactor vessel, the interior being defined by an interior wall of thereactor vessel; a liquid distributor assembly located below and in fluidcommunication with the inlet for discharging the liquid feedstockradially outward towards the interior walls of the reactor vessel; abasket located within the reactor vessel interior and below the liquiddistributor assembly, the basket having a fluid permeable outer wall anda first fluid permeable inner wall that is spaced radially inward fromthe outer wall to define a first annular interior space of the basket,the first annular interior space of the basket containing a particulatematerial for removing contaminants from the liquid feedstock, the outerwall of the basket being spaced radially inward from the interior wallof the reactor vessel to define an annular flow space between the outerwall of the basket and the interior wall of the reactor vessel, andwherein liquid feedstocks introduced into the reactor vessel from theliquid distributor assembly flow through the annular flow space andradially inward through the first annular interior space of the basketand through the particulate material to facilitate removal ofcontaminants from the liquid feedstock to form a purified feedstock, thefirst fluid permeable inner wall forming a purified feedstock outlet ofthe basket and defining a central conduit that extends along the lengthof the basket, the central conduit having a conduit outlet fordischarging the purified feedstock; and a catalyst that is locatedwithin the reactor vessel and in fluid communication with the purifiedfeedstock outlet of the basket for contacting the purified feedstock toform a desired product.
 2. The reactor of claim 1, wherein: the lengthof the basket Lb is:L _(b)=(D _(r) ²/4D _(b))(ψ) where D_(r) is the interior diameter of thereactor vessel, D_(b) is the diameter of the fluid permeable outer wallof the basket, and ψ is a coefficient ranging from 1 to 20 correspondingto a cycle life of a pretreatment bed formed by the particulate materialcontained within the basket, with L_(b) being less than or equal to thelength of the reactor vessel.
 3. The reactor of claim 1, wherein: theinterior diameter of the reactor vessel is D_(r) and the liquiddistributor assembly is configured to provide a stagnation head h_(s) ofintroduced liquids where h_(s)≤D_(r)/2.
 4. The reactor of claim 1,wherein: the outlet of the basket is configured to provide a pressuredrop ΔP across the fluid permeable inner wall of from 2 to 10 times thevelocity head h_(v) at the conduit outlet.
 5. The reactor of claim 1,wherein: the basket is a segregated basket wherein a second fluidpermeable inner wall is spaced radially inward from the first fluidpermeable inner wall to define a second annular interior space, thesecond fluid permeable inner wall defining the central conduit, andwherein the second annular interior space contains a second particulatematerial.
 6. The reactor of claim 5, wherein: the second particulatematerial is a different particulate material for removing contaminants.7. The reactor of claim 5, wherein: the second particulate material is acatalyst.
 8. The reactor of claim 1, wherein: the catalyst is ahydroprocessing catalyst.
 9. The reactor of claim 1, wherein: the basketis covered at an upper end to prevent the passage of fluids through theupper end of the basket.
 10. A method of producing a product from highcontaminant liquid feedstocks, the method comprising: introducing fluidscomprising a liquid feedstock containing contaminants into a reactor,the reactor comprising: a reactor vessel having an inlet for introducingthe liquid feedstock into an interior of the reactor vessel, theinterior being defined by an interior wall of the reactor vessel; aliquid distributor assembly located below and in fluid communicationwith the inlet for discharging the liquid feedstock radially outwardtowards the interior walls of the reactor vessel; a basket locatedwithin the reactor vessel interior and below the distributor assembly,the basket having a fluid permeable outer wall and a first fluidpermeable inner wall that is spaced radially inward from the outer wallto define a first annular interior space of the basket, the firstannular interior space of the basket containing a particulate materialfor removing contaminants from the liquid feedstock, the outer wall ofthe basket being spaced radially inward from the interior wall of thereactor vessel to define an annular flow space between the outer wall ofthe basket and the interior wall of the reactor vessel, the first fluidpermeable inner wall forming a purified feedstock outlet of the basketand defining a central conduit that extends along the length of thebasket, the central conduit having a conduit outlet for discharging thepurified feedstock; and a catalyst that is located within the reactorvessel and in fluid communication with the purified feedstock outlet ofthe basket for contacting the purified feedstock to form a desiredproduct; and introducing the liquid feedstock into the inlet of thereactor vessel and allowing the feedstock to flow into and through theliquid distributor assembly, the liquid feedstock being dischargedradially outward towards the interior walls of the reactor vessel andthrough the annular flow space wherein the liquid feedstock flowsradially inward through the first annular interior space of the basketand through the particulate material so that contaminants are removedfrom the liquid feedstock to form a purified feedstock; and contactingthe purified feedstock with the catalyst to form a desired product. 11.The method of claim 10, wherein: the length of the basket Lb, wherein:L _(b)=(D _(r) ²/4D _(b))(ψ) where D_(r) is the interior diameter of thereactor vessel, D_(b) is the diameter of the fluid permeable outer wallof the basket, and ψ is a coefficient ranging from 1 to 20 correspondingto a cycle life of a pretreatment bed formed by the particulate materialcontained within the basket, with L_(b) being less than or equal to thelength of the reactor vessel.
 12. The method of claim 10, wherein: theannular flow space has a circumferential gap co that provides sufficientflow space so that the average liquid flow velocity through the annularflow space is the same as the average liquid flow velocity of theliquids discharged from the distributor assembly.
 13. The method ofclaim 10, wherein: the fluids further comprise at least one of a diluentand hydrogen.
 14. The method of claim 10, wherein: the interior diameterof the reactor vessel is D_(r) and the liquid distributor assembly isconfigured to provide a stagnation head h_(s) of introduced liquidswhere h_(s)≤D_(r)/2.
 15. The method of claim 10, wherein: the outlet ofthe basket is configured to provide a pressure drop ΔP across the fluidpermeable inner wall of from 2 to 10 times the velocity head h_(v) atthe conduit outlet.
 16. The method of claim 10, wherein: the basket is asegregated basket wherein a second fluid permeable inner wall is spacedradially inward from the first fluid permeable inner wall to define asecond annular interior space, the second fluid permeable inner walldefining the central conduit, and wherein the second annular interiorspace contains a second particulate material.
 17. The method of claim15, wherein: the second particulate material is a different particulatematerial for removing contaminants.
 18. The method of claim 15, wherein:the second particulate material is a catalyst.
 19. The method of claim10, wherein: the catalyst is a hydroprocessing catalyst.
 20. The methodof claim 10, wherein: at least one of the liquid feedstock and purifiedfeedstock contains metal contaminants, and further comprising: combiningthe at least one of the liquid feedstock and purified feedstockcontaining metal contaminants with a metal-removal additive, andoptionally hydrogen; allowing the metal-removal additive to react withthe metals of the at least one of the liquid feedstock and purifiedfeedstock to form a metal-containing precipitate; and removing themetal-containing precipitate from the at least one of the liquidfeedstock and purified feedstock; and then at least one of a)introducing the liquid feedstock into the inlet of the reactor vessel,and b) contacting the purified feedstock with the catalyst to form thedesired product.